Novel pH-responsive mixed-charge copolymer brushes based on carboxylic acid and quaternary amine monomers



In this study, we report on the fabrication of tunable mixed-charged copolymer brushes consisting of negatively charged carboxylic acid monomer (4-vinylbenzoic acid, VBA) and positively charged quaternary amine monomer ((ar-vinylbenzyl)trimethylammonium chloride) via reversible addition–fragmentation chain transfer-mediated polymerization. The copolymer brushes have negative charge under neutral and basic conditions, and are positively charged under acidic conditions owing to the protonation of the carboxylate groups. The copolymer brushes revealed a unique reversible wetting behavior with pH. The reversible properties of the copolymer brushes can be employed to regulate the adsorption of charged biomacromolecules such as DNA and proteins. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013